feat(command-flow): use microtask for scheduling

Author: Char2sGu

packages/command-flow/src/scheduler.ts

@@ -1,8 +1,16 @@
 import { forwardRef, inject, Injectable, PendingTasks } from '@angular/core';
 
+/**
+ * Service that schedules a function to be executed after the current
+ * execution context is completed.
+ *
+ * Uses `MicrotaskCommandFlowScheduler` by default.
+ *
+ * This is usually used to schedule the dispatch of command events.
+ */
 @Injectable({
   providedIn: 'root',
-  useExisting: forwardRef(() => SetTimeoutCommandFlowScheduler),
+  useExisting: forwardRef(() => MicrotaskCommandFlowScheduler),
 })
 export abstract class CommandFlowScheduler {
   abstract next(fn: () => void): void;
@@ -26,6 +34,22 @@ export class SetTimeoutCommandFlowScheduler implements CommandFlowScheduler {
   }
 }
 
+/**
+ * Implementation of {@link CommandFlowScheduler} that uses
+ * `queueMicrotask` to schedule the next execution.
+ * The scheduled function is added to {@link PendingTask} for SSR support.
+ */
+export class MicrotaskCommandFlowScheduler implements CommandFlowScheduler {
+  #tasks = inject(PendingTasks);
+  next(fn: () => void): void {
+    const done = this.#tasks.add();
+    queueMicrotask(() => {
+      fn();
+      done();
+    });
+  }
+}
+
 /**
  * Implementation of {@link CommandFlowScheduler} that uses
  * `requestAnimationFrame` to schedule the next execution.